Pro: Stuck to the main story. Good acting & special effects.
Con: Weak ending/epilogue, but it was the same as the book. Overall, the movie somehow never quite connected.
What to say after that? A rather large sub-plot in the book (in which Card essentially predicts the blogosphere having a heavy influence on politics) was neatly excised from the story. It wasn't needed here, would've weighted things down, and isn't really adaptable to a movie. Even though it's a spectacular sci-fi coup for Card, dropping it from the script was a good call.
After that, so much of the story is Ender's personal inner struggle. It's hard to get something like that on film. Guess the director did his best. It sorta worked, but not quite.
BUT. Here is the noteworthy thing about this film: It stuck to the story. Whatever else its flaws, it stuck to the story. They didn't bring in some hack writer, toss out the book, keep the tile and a couple of characters' names, and con everybody into a big opening weekend (example, and yes my prediction for that movie panned out). For once, Hollywood stuck to the story, and the results – despite the novel's problems – were pretty good.
Three out of four stars. If it interests you at all, go see it!